How should I backlink this?

Hello everybody!

I'm in a dilemma. I have no idea how to do this. My site is xxx.net (xxx to hide my domain name) and is ranking for xxx. My articles, however, target xxx xyz, each article tagetting a different xyz (for example, one article, or xyz, could be about dogs, and the other article, or xyz, could be about cats, and xxx is the main niche, animals, and the xxx doesn't change. (No, that's not my real niche. It's jsut for demonstartion purposes )). They are at around the 7th position when it comes to the serps when I search for xxx xyz. I get decent traffic (150k/month).

Now what I'm wondering is how I should backlink this. My usual plan is to backlink the main domain, or in this example, xxx.net, but I am doubting that it really affects the SERPS when it comes to the specific keywords in an article. I would try to backlink the article for xxx xyz, but since I have over 150 articles, also meaning 150 different xyz's, I think this would look unnatural to just backlink a few and not backlink the rest.

Keep in mind that I'm a noob at this and I'm thinking of using secretboy08's service.

Any help would be appreciated

Anyone?

I don't see anything unnatural in linking to some pages and not linking to others. Give it a go - that's the only way to find it out for sure, no one can tell you "a priori" these days.